2021-09-13

No nucleic acid was found for 9 times, and the diagnosis was only 38 days after entering the country…Is the quarantine period lengthened?

By yqqlm yqqlm

Chinanews client, Beijing, September 13 (Peng Ningling) On the 12th, 22 new local confirmed cases were added in Fujian. The epidemic that started in Putian has now spread to Xiamen and Quanzhou.

According to the previous Putian report, Lin Moumou, who was suspected of being the source of the epidemic, had been in the country for 38 days when he was diagnosed, and the results of 9 nucleic acid tests were negative, and 1 serum test was also negative. This information brought the topic of the virus’ “ultra-long incubation period” back into focus. So, how to calculate the “extra-long incubation period”? Do you need to adjust prevention and control measures?

No nucleic acid was found for 9 times, and the diagnosis was only 38 days after entering the country…Is the quarantine period lengthened?

September 12, Medical staff sampled nucleic acid for students of Fuzhou University. Photo by Fan Xinchen

The diagnosis is only 38 days after entering the country. New changes in Delta?

In the official notification on September 10, Lin Moumou (38 years old, Singaporean immigrant, student parent), who was suspected of being the source of the epidemic, was introduced.

According to the current investigation, it was discovered that Lin Moumou was a returnee from abroad. He entered Xiamen Airport from Singapore on Xiamen Airlines flight MF852 on August 4 and was quarantined at a designated hotel in Xiamen for 14 days on August 19. Point-to-point transfer to Xianyou County centralized isolation point to continue centralized isolation.

According to Fujian Province’s epidemic prevention and control measures, Lin Moumou began to implement 7-day home health monitoring on August 26 after completing the “14+7” day of centralized quarantine.

Ling Longmei, director of the Putian Center for Disease Control and Prevention, stated that the imported cases from outside Singapore were quarantined for 21 days, during which 9 nucleic acid tests were negative, and 1 serum test was also negative. Nucleic acid on September 10 The test result is positive, and the virus has a longer incubation period. In addition, Putian also introduced that the specimens of the epidemic-related cases have been sent to the Provincial Center for Disease Control and Prevention for genetic sequencing, and the results were preliminarily determined to be the Delta strain.

None of the nucleic acid tests were positive for 38 days and 9 times after entering the country. Is this inconsistent with previous studies that the Delta strain has a short incubation period and rapid onset? Does it mean new changes in the virus?

Recently, a public health expert said in an interview with the media that this situation cannot be completely ruled out, but it is necessary to first rule out other possibilities such as false negatives caused by testing reagents, testing operations and sampling. .

Peng Zhiyong, director of the Department of Critical Care Medicine, Zhongnan Hospital of Wuhan University, told the Global Times that according to previous observations, about 95% to 99% of infected persons can be screened during the set centralized quarantine observation period Come out, but it is inevitable that there will be individual extreme situations.

“The general characteristics of the Delta strain are that one is strong infectivity, and the other is high viral load and high viral load. In fact, it also means that it is easy to be screened. It appears that the Delta strain is actually easier to find than the previous strains.” Peng Zhiyong said.

No nucleic acid was found for 9 times, and the diagnosis was only 38 days after entering the country…Is the quarantine period lengthened?(1)

The medical staff is Fuzhou University Student nucleic acid sampling. Photo by Fan Xinchen

Is the virus too cunning, or is there loopholes in prevention and control?

With regard to the “extra-long incubation period”, Lin Moumou of Putian City is indeed not the first case.

As early as the beginning of this year, in many cases of COVID-19, there were also multiple rounds of nucleic acid tests before they turned from negative to positive: A case in Dalian showed positive results in 11 nucleic acid tests, Shunyi, Beijing Individual close contacts who tested positive after 14 days of isolation have caused concern.

Recently, in addition to Putian, Fujian, there has also been a case of negative-to-positive nucleic acid detection in Guangzhou, Guangdong.

According to the news on the official website of the Guangzhou Municipal Health Commission on September 10, there was a new case of close contact with the new coronavirus nucleic acid positive case in Guangzhou. The case began to undergo centralized isolation medical observation on September 4. During the isolation period, the nucleic acid test results of the new coronavirus were all negative, and the nucleic acid test was positive on September 10.

According to a report by the China Broadcasting Corporation on January 17 this year, Feng Zijian, deputy director of the China Centers for Disease Control and Prevention, analyzed, “(Nucleic acid testing changes from negative to positive). There are many reasons. The number of people is increasing, and the disease is diversified. There may be rare cases of long incubation period, or it may be that the sensitivity of the nucleic acid test reagent when the close contact is released from quarantine, and it may be that the close contact was infected during the quarantine. , A variety of situations may exist.”

How to calculate the incubation period of the new coronavirus? In February last year, Cai Weiping, an expert in the treatment team of the Guangdong New Coronary Pneumonia Prevention and Control Headquarters and director of the Infectious Diseases Center of the Eighth People’s Hospital of Guangzhou City, once introduced that the “incubation period” refers to the time from a patient’s infection with the virus to the appearance of the first symptoms, rather than a nucleic acid test. The result is calculated as positive; only those with symptoms can define the “incubation period”.

In answering whether there is an “extra-long incubation period”, Cai Weiping said that it was because some patients had milder symptoms and were ignored. He believes that it is difficult to say whether there is an “extra-long incubation period”.

It is worth mentioning that in February last year, the team of Academician Zhong Nanshan published a paper in the international top medical journal “New England Journal of Medicine”. The study found that among 1,099 patients with new coronavirus infections, There is an incubation period of 24 days in each of the severe and non-severe patients with new coronary pneumonia.

In this regard, Academician Zhong Nanshan said that the long incubation period of 24 days is only an exception, and it is not surprising that there are always exceptions.

No nucleic acid was found for 9 times, and the diagnosis was only 38 days after entering the country…Is the quarantine period lengthened?(2)

Guangzhou Baiyun Airport. All inbound flights from Fujian to Guangzhou are included in key control. Photo by Lin Yican

For the “extra-long incubation period” cases that appeared in the Putian epidemic, how to protect is still the most concerned issue.

Relevant experts said that the “extra-long incubation period” is not common and cannot be regarded as a common situation. Strengthening vaccination and personal daily protection are still the top priorities.

For example, regarding the prevention and control of Delta, at present, prevention and control experts generally believe that the existing vaccines still have a good preventive and protective effect on the Delta strain, and can reduce the risk of virus transmission in the population. , To reduce the transmission power of infected persons, and effectively reduce the incidence of severe illness and mortality after infection.

In view of the hidden danger of “ultra-long incubation period”, some regions are also exploring and upgrading prevention and control methods.

In January this year, in order to effectively deal with the risk of transmission of infected persons with a long incubation period and the risk of imported epidemics at home and abroad, Beijing adjusted and strengthened the prevention and control measures for people entering Beijing from abroad and All close contacts in Beijing are classified and implemented “14+7+7” management measures.

So, how long is the isolation period before insurance? Many experts have analyzed that extending the time of centralized isolation can reduce the risk of virus transmission to a certain extent, but as the virus continues to mutate, it is still impossible to rule out the extreme situation of long-term virus carriers.

Some experts also believe that the next step should be to focus on optimizing the development of better antibody detection reagents. In addition, it is not enough for the prevention and control of the new crown epidemic to just highlight the “isolation of people”. International cargo transportation also exposes a lot of At the same time, it is necessary to strengthen entry testing and restrictions on animals from epidemic areas carrying the new crown virus. (End)